Boeing has once again found itself in the doghouse.

Last week, Boeing invited dozens of reporters from around the world—including me, a local Seattleite—to its 737 production facility in Renton, Washington, to highlight improvements to its safety and quality culture.

Ironically, comments made during a briefing on its new safety and quality improvement plan landed Boeing in hot water with the National Transportation Safety Board (NTSB), which slapped the company with sanctions the next day.

Before laying out the details of its FAA-ordered safety and quality overhaul, Elizabeth Lund—senior v-p of quality at Boeing’s commercial airplanes division—made brief remarks about the January 5 incident in which a mid-exit door plug blew out of an Alaska Airlines 737 Max 9 departing from Portland, Oregon.

According to the NTSB, Lund’s comments contained unreleased and unverified details about its ongoing investigation and amounted to “blatant violations” of federal regulations and the terms of Boeing’s party agreement to the investigation. In response, the NTSB rescinded Boeing’s access to investigative materials and filed a complaint with the Department of Justice, which is also separately charging Boeing for crimes pertaining to the fatal Max crashes in 2018 and 2019.

In case you need a refresher, here’s what the NTSB has publicly said about the door plug fiasco so far: Four retaining bolts intended to hold the plug in place were missing when the airplane left the Renton factory last year. Records showed that the door plug had been removed so that technicians at Spirit AeroSystems, Boeing’s fuselage supplier, could access nearby rivets for repairs. Whoever subsequently closed the door plug did not reinstall the bolts.

In a perplexing plot twist, Lund revealed during the June 25 briefing that Boeing does not believe the mechanics who reinstalled the door plug are to blame for the missing bolts. Rather, Boeing believes that a missing piece of paperwork caused a breakdown in its processes that led an aircraft to roll off the production line without those bolts in place.

Lund explained that a so-called “move crew” at the Renton factory closed the door plug before moving the airplane outside the factory. “We know the move crew closed the plug. They did not reinstall the retaining pins. That is not their job. Their job is to just close it and they count on existing paperwork.”

Exactly whose job it was to file that crucial piece of paperwork remains a mystery that Lund said is up to the NTSB to solve—although the NTSB disputed the notion that its mission is to name names or point fingers.

Perhaps an even bigger mystery, though, is how one simple piece of paperwork became a single point of failure. “The fact that one employee could not fill out one piece of paperwork in this condition and could result in an accident was shocking to all of us,” Lund said.

The NTSB’s rebuke calls into question Lund’s account of the events that led up to the door plug debacle. But one thing is for certain: Boeing screwed up—again.

Boeing billed the two-day-long media gathering in Washington as a preview for the Farnborough International Airshow, where the plane-maker typically announces new orders or products. But this year, it dedicated the event to convincing the media that its airplanes are safe at a time when public trust in the company is at an all-time low.

In describing the actions it has taken to fix its quality control problems, Boeing painted a convincing picture of a system that appears to be fail-safe. But we’ve heard Boeing say similar things before, and the company’s deficient safety culture has nevertheless persisted.

Lund said that this time with the door plug is different from the situation that caused the 737 Max crashes because it was a manufacturing issue rather than an engineering issue. But this comparison between the causes of the accidents doesn’t really help Boeing’s case, because it indicates an even deeper problem.

Deficiencies in Boeing’s safety culture extend beyond any particular program or process. It’s a systemic issue that reaches up the company’s corporate ladder all the way to its chief executives. Only a change in leadership can bring about effective changes to the company’s culture.

We saw Boeing oust its previous CEO in the aftermath of the Max crashes, and its new CEO is now planning to step down by year-end. We can only hope that whoever Boeing selects as its next CEO will be able to bring meaningful change.